Purpose: :
To evaluate the hypothesis that gas tamponade after repair ofretinal detachment significantly alters fluid dynamics withinthe posterior chamber which reduces the risk of re-detachmentof the retina during the critical period after detachment repair

Methods: :
Computational theoretical modelling and analysis of fluid movementand shear forces on the retinal wall were evaluated in the presenceof varying degrees of gas and fluid fill within a simulatedmodel of the eye. The same parameters were examined during angulardisplacement and recti-linear acceleration of the globePracticalexperiments using a clear Perspex eye model were examined withthe same variables and compared to theoretical predictions.A dark fluid was used to fill the eye and fluid dynamics wereevaluated through analysis of light passage through the fluidusing specific software.

Results: :
The shear stress on the interior of the model depends on whetherit is wetted by the liquid. High gas fill decreases the fractionof surface which experiences a large shear stress and also decreasesliquid sloshing due to the eye movement. Rapid angular displacementof the eye (around a vertical axis) creates a shear stress ofmagnitude ~0.01Pa on the retina (which is maximum near the liquid/ air interface). Rapid rectilinear acceleration (movement of~1m/s in 0.1 s) increases the shear stress by two-orders ofmagnitude to ~1 Pa. The largest shear stress is concentratedaround a vertical band along the eye wall perpendicular to thedirection of movement. These numerical results are supportedby the mathematical models and the physical model of the eye.

Conclusions: :
Gas tamponade after retinal detachment repair significantlyalters posterior chamber fluid dynamics and reduces fluid shearon the retinal wall. This may be an important factor which reducesrisk of re-detachment of the retina.